* Linus Torvalds [Thu, 01 Jan 2009 11:45:21 -0800]:
> On Thu, 1 Jan 2009, Johannes Schindelin wrote:
> > Nothing fancy, really, just a straight-forward implementation of the
> > heavily under-documented and under-analyzed paience diff algorithm.
> Exactly because the patience diff is so under-documented, could you
> perhaps give a few examples of how it differs in the result, and why it's
> so wonderful? Yes, yes, I can google, and no, no, nothing useful shows up
> except for *totally* content-free fanboisms.
> So could we have some actual real data on it?
For me, the cases where I find patience output to be of substantial
higher readability are those involving a rewrite of several consecutive
paragraphs (i.e., lines of code separated by blank lines). Compare:
-8<- git -8<-
@@ -51,29 +51,30 @@ def mbox_update(bug):
f.close()
else:
# make a list of Message-Id we have
- fp1 = file(path, 'ab+')
- ids1 = [ x.get('Message-Id') for x in mailbox.UnixMailbox(fp1) ]
+ msgids = { x.get('Message-Id') for x in mailbox.mbox(path) }
- # get remote mbox again
- fp2 = tempfile.TemporaryFile()
- retrieve_mbox(bug, fp2)
+ with tempfile.NamedTemporaryFile() as tmpfd:
+ # retrieve the remote mbox again
+ retrieve_mbox(bug, tmpfd)
- # parse its messages
- fp2.seek(0)
- parser = email.Parser.Parser()
- msgs2 = dict((x['Message-Id'], x)
- for x in mailbox.UnixMailbox(fp2, parser.parse))
+ # parse its messages
+ parser = email.parser.Parser()
+ new_msgids = { x['Message-Id']: x
+ for x in mailbox.mbox(tmpfd.name, parser.parse) }
- # now append the new ones
- for msgid in set(msgs2.keys()) - set(ids1):
- fp1.write('\n' + msgs2[msgid].as_string(unixfrom=True))
+ with open(path, 'a+') as fd:
+ # now append the new messages
+ for msgid in new_msgids.keys() - msgids:
+ fd.write('\n' + new_msgids[msgid].as_string(unixfrom=True))
return path
->8- git ->8-
with:
-8<- bzr patience -8<-
@@ -51,29 +51,30 @@
f.close()
else:
# make a list of Message-Id we have
- fp1 = file(path, 'ab+')
- ids1 = [ x.get('Message-Id') for x in mailbox.UnixMailbox(fp1) ]
-
- # get remote mbox again
- fp2 = tempfile.TemporaryFile()
- retrieve_mbox(bug, fp2)
-
- # parse its messages
- fp2.seek(0)
- parser = email.Parser.Parser()
- msgs2 = dict((x['Message-Id'], x)
- for x in mailbox.UnixMailbox(fp2, parser.parse))
-
- # now append the new ones
- for msgid in set(msgs2.keys()) - set(ids1):
- fp1.write('\n' + msgs2[msgid].as_string(unixfrom=True))
+ msgids = { x.get('Message-Id') for x in mailbox.mbox(path) }
+
+ with tempfile.NamedTemporaryFile() as tmpfd:
+ # retrieve the remote mbox again
+ retrieve_mbox(bug, tmpfd)
+
+ # parse its messages
+ parser = email.parser.Parser()
+ new_msgids = { x['Message-Id']: x
+ for x in mailbox.mbox(tmpfd.name, parser.parse) }
+
+ with open(path, 'a+') as fd:
+ # now append the new messages
+ for msgid in new_msgids.keys() - msgids:
+ fd.write('\n' + new_msgids[msgid].as_string(unixfrom=True))
return path
->8- bzr patience ->8-
I don't know about you, but I find the latter much easier to read,
because the whole context of each version is always available.
As you see, in (at least) this case is just a matter of considering the
blank lines worthy of presented as common, or not.
I'll note that in this particular case, `git diff` yielded the very same
results with or without --patience. I don't know why that is, Johannes?
I'll also note that /usr/bin/diff produces (in this case) something
closer to patience than to git.
I'm attaching both versions of the file in case they are useful to
anybody.
--
Adeodato Simó dato at net.com.org.es
Debian Developer adeodato at debian.org
I promise you. Once I enter into an exclusive relationship, I sleep with
very few people.
-- Denny Crane
#! /usr/bin/python
## vim: fileencoding=utf-8
"""Open Debian BTS mboxes with Mutt, à la /usr/bin/bts show --mbox.
A cache of mboxes is kept, and changed mboxes will be merged with existing
files instead of replacing them, so that e.g. read-status is preserved for each
message.
"""
import os
import re
import sys
import urllib
import mailbox
import tempfile
import email.Parser
MBOX_DIR = os.path.expanduser('~/.mail/y.bug-cache')
##
def main():
if len(sys.argv) != 2:
print >>sys.stderr, 'Usage: %s <bugnumber>' % (sys.argv[0],)
sys.exit(1)
bug = re.sub(r'[^0-9]', '', sys.argv[1])
if not re.match(r'\d{4,}$', bug):
print >>sys.stderr, \
'E: %s does not seem a valid number' % (sys.argv[1],)
sys.exit(1)
path = mbox_update(bug)
invoke_mailer(path)
##
def mbox_update(bug):
"""Return a path with an up-to-date copy of the mbox for bug."""
path = os.path.join(MBOX_DIR, bug + '.mbox')
if not os.path.exists(path):
f = file(path, 'wb')
try:
retrieve_mbox(bug, f)
except:
os.unlink(path)
raise
else:
f.close()
else:
# make a list of Message-Id we have
fp1 = file(path, 'ab+')
ids1 = [ x.get('Message-Id') for x in mailbox.UnixMailbox(fp1) ]
# get remote mbox again
fp2 = tempfile.TemporaryFile()
retrieve_mbox(bug, fp2)
# parse its messages
fp2.seek(0)
parser = email.Parser.Parser()
msgs2 = dict((x['Message-Id'], x)
for x in mailbox.UnixMailbox(fp2, parser.parse))
# now append the new ones
for msgid in set(msgs2.keys()) - set(ids1):
fp1.write('\n' + msgs2[msgid].as_string(unixfrom=True))
return path
def retrieve_mbox(bug, fileobj):
"""Retrieve mbox for bug from bugs.debian.org, writing it to fileobj."""
for line in urllib.urlopen(
'http://bugs.debian.org/cgi-bin/bugreport.cgi?mboxstatus=yes;mboxmaint=yes;mbox=yes;bug=%s' % (bug,)):
fileobj.write(line)
def invoke_mailer(path):
"""Exec mutt, opening path."""
os.execlp('mutt', 'mutt', '-f', path)
##
if __name__ == '__main__':
try:
sys.exit(main())
except KeyboardInterrupt:
print >>sys.stderr, '\nCancelled.'
sys.exit(1)
#! /usr/bin/python3
"""Open Debian BTS mboxes with Mutt, à la /usr/bin/bts show --mbox.
A cache of mboxes is kept, and changed mboxes will be merged with existing
files instead of replacing them, so that e.g. read-status is preserved for each
message.
"""
import os
import re
import sys
import mailbox
import tempfile
import email.parser
import urllib.request
MBOX_DIR = os.path.expanduser('~/.mail/y.bug-cache')
##
def main():
if len(sys.argv) != 2:
print('Usage: {0} <bugnumber>'.format(sys.argv[0]), file=sys.stderr)
return 1
else:
bug = re.sub(r'[^0-9]', '', sys.argv[1])
if not re.search(r'^\d{4,}$', bug):
print('E: {0} does not seem a valid number'.format(sys.argv[1]),
file=sys.stderr)
return 1
path = mbox_update(bug)
invoke_mailer(path)
##
def mbox_update(bug):
"""Return a path with an up-to-date copy of the mbox for bug."""
path = os.path.join(MBOX_DIR, bug + '.mbox')
if not os.path.exists(path):
f = open(path, 'wb')
try:
retrieve_mbox(bug, f)
except:
os.unlink(path)
raise
else:
f.close()
else:
# make a list of Message-Id we have
msgids = { x.get('Message-Id') for x in mailbox.mbox(path) }
with tempfile.NamedTemporaryFile() as tmpfd:
# retrieve the remote mbox again
retrieve_mbox(bug, tmpfd)
# parse its messages
parser = email.parser.Parser()
new_msgids = { x['Message-Id']: x
for x in mailbox.mbox(tmpfd.name, parser.parse) }
with open(path, 'a+') as fd:
# now append the new messages
for msgid in new_msgids.keys() - msgids:
fd.write('\n' + new_msgids[msgid].as_string(unixfrom=True))
return path
def retrieve_mbox(bug, fileobj):
"""Retrieve mbox for bug from bugs.debian.org, writing it to fileobj."""
url = urllib.request.urlopen(
'http://bugs.debian.org/cgi-bin/bugreport.cgi?'
'mboxstatus=yes;mboxmaint=yes;mbox=yes;bug={0}'.format(bug))
for line in url.fp: # http://bugs.python.org/issue4608
fileobj.write(line)
def invoke_mailer(path):
"""Exec mutt, opening path."""
os.execlp('mutt', 'mutt', '-f', path)
##
if __name__ == '__main__':
try:
sys.exit(main())
except KeyboardInterrupt:
print('\nCancelled.', file=sys.stderr)
sys.exit(1)
